If you are a python developer and have recently updated to the new OS X Mavericks, you might be getting a series of new error messages. Here are a few steps that may help you fix some of the problems that have come from the new update.

However, before you begin make sure you have updated to the latest version of the operating system, as well as Xcode Command Line Tools.

You can install the Xcode Command Line tools directly from the CLI:

$ xcode-select --install

distribution

The very first problem after upgrading was a DistributionNotFound exception being through by pip. Since I have my terminal setup to use ZSH, it attempts to source virtualenvwrapper.sh on startup. When launching iTerm, I was immediately shown the following:

Traceback (most recent call last):
  File "/usr/local/bin/pip", line 5, in
    from pkg_resources import load_entry_point
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 2603, in
    working_set.require(__requires__)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 666, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 565, in resolve
    raise DistributionNotFound(req)  # XXX put more info here

The error message was a little unhelpful, and some of the Google search results were either outdated or incomplete. However, I was able to put together a few pieces of information on my Twitter feed from other developers encountering the same problem. My actual problem was that my machine's installation of setuptools and distribute was outdated. The following commands download ez_setup securely and update your installation:

$ wget https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py
$ sudo python ez_setup.py

virtualenv wrapper

After fixing the original problem around distribution error message, I encountered another problem with virtualenvwrapper:

/usr/bin/python: No module named virtualenvwrapper
virtualenvwrapper.sh: There was a problem running the initialization hooks.

If Python could not import the module virtualenvwrapper.hook_loader,
check that virtualenv has been installed for
VIRTUALENVWRAPPER_PYTHON=/usr/bin/python and that PATH is
set properly.

This one actually turned out to be an easy fix. I just needed to force a reinstall of pip and virtualenvwrapper with the following:

$ sudo easy_install pip
$ sudo pip install --upgrade virtualenvwrapper